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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2019-02-07 13:10:46 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2019-02-07 13:11:13 -0500 |
| commit | 9d6d2b21343db76a769fbcae72fbcbc18aa388cb (patch) | |
| tree | b549a4fc73d9322ccec8a56f6414cb099f6fda73 /contrib/postgres_fdw/postgres_fdw.c | |
| parent | 8722d2cbc0500b8ae1ebaf0a388115617615c1eb (diff) | |
| download | postgresql-9d6d2b21343db76a769fbcae72fbcbc18aa388cb.tar.gz postgresql-9d6d2b21343db76a769fbcae72fbcbc18aa388cb.zip | |
Ensure that foreign scans with lateral refs are planned correctly.
As reported in bug #15613 from Srinivasan S A, file_fdw and postgres_fdw
neglected to mark plain baserel foreign paths as parameterized when the
relation has lateral_relids. Other FDWs have surely copied this mistake,
so rather than just patching those two modules, install a band-aid fix
in create_foreignscan_path to rectify the mistake centrally.
Although the band-aid is enough to fix the visible symptom, correct
the calls in file_fdw and postgres_fdw anyway, so that they are valid
examples for external FDWs.
Also, since the band-aid isn't enough to make this work for parameterized
foreign joins, throw an elog(ERROR) if such a case is passed to
create_foreignscan_path. This shouldn't pose much of a problem for
existing external FDWs, since it's likely they aren't trying to make such
paths anyway (though some of them may need a defense against joins with
lateral_relids, similar to the one this patch installs into postgres_fdw).
Add some assertions in relnode.c to catch future occurrences of the same
error --- in particular, as backstop against core-code mistakes like the
one fixed by commit bdd9a99aa.
Discussion: https://postgr.es/m/15613-092be1be9576c728@postgresql.org
Diffstat (limited to 'contrib/postgres_fdw/postgres_fdw.c')
| -rw-r--r-- | contrib/postgres_fdw/postgres_fdw.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c index f0be58f60c7..fea288e8ebb 100644 --- a/contrib/postgres_fdw/postgres_fdw.c +++ b/contrib/postgres_fdw/postgres_fdw.c @@ -930,6 +930,9 @@ postgresGetForeignPaths(PlannerInfo *root, * baserestrict conditions we were able to send to remote, there might * actually be an indexscan happening there). We already did all the work * to estimate cost and size of this path. + * + * Although this path uses no join clauses, it could still have required + * parameterization due to LATERAL refs in its tlist. */ path = create_foreignscan_path(root, baserel, NULL, /* default pathtarget */ @@ -937,7 +940,7 @@ postgresGetForeignPaths(PlannerInfo *root, fpinfo->startup_cost, fpinfo->total_cost, NIL, /* no pathkeys */ - NULL, /* no outer rel either */ + baserel->lateral_relids, NULL, /* no extra plan */ NIL); /* no fdw_private list */ add_path(baserel, (Path *) path); @@ -4978,7 +4981,7 @@ add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel, startup_cost, total_cost, useful_pathkeys, - NULL, + rel->lateral_relids, sorted_epq_path, NIL)); } @@ -5116,6 +5119,13 @@ postgresGetForeignJoinPaths(PlannerInfo *root, return; /* + * This code does not work for joins with lateral references, since those + * must have parameterized paths, which we don't generate yet. + */ + if (!bms_is_empty(joinrel->lateral_relids)) + return; + + /* * Create unfinished PgFdwRelationInfo entry which is used to indicate * that the join relation is already considered, so that we won't waste * time in judging safety of join pushdown and adding the same paths again @@ -5206,7 +5216,7 @@ postgresGetForeignJoinPaths(PlannerInfo *root, startup_cost, total_cost, NIL, /* no pathkeys */ - NULL, /* no required_outer */ + joinrel->lateral_relids, epq_path, NIL); /* no fdw_private */ @@ -5534,7 +5544,7 @@ add_foreign_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel, startup_cost, total_cost, NIL, /* no pathkeys */ - NULL, /* no required_outer */ + grouped_rel->lateral_relids, NULL, NIL); /* no fdw_private */ |